This invention relates to a ballistic trajectory simulation method wherein a ballistic trajectory of a golf ball having a plurality of dimples formed on the surface thereof is estimated by setting a golf ball model on a computer and making use of arithmetic operation by the computer to calculate kinetic elements of the golf ball model and a flight simulation method wherein a flight state of a golf ball which flies along a trajectory obtained by the ballistic trajectory simulation method is analyzed.
It is known that, when such a physical solid as a golf ball flies in the atmospheric air, turbulence of an air current appears around the physical solid. If the surface of the physical solid has a complicated shape or if the physical solid flies while rotating, then the turbulence of an air current during the flight is complicated and has a significant influence on the flight performance such as the flight distance of the physical solid.
In most cases, a large number of dimples of a circular shape as viewed in plan are provided on a golf ball. Since the combination of a three-dimensional shape, arrangement and size of the dimples has a significant influence on the aerodynamic characteristics of the golf ball, it is necessary to grasp the causal relation between the dimple factors and the aerodynamic characteristics.
Usually, in order to investigate the influence of a change in shape, structure, arrangement or the like of the dimples on the flight performance of the golf ball, various molds for molding golf balls are produced to produce various ball models, and a hitting experiment of the balls is performed to measure the initial speed, spin, ballistic trajectory (flight distance, height) and so forth to evaluate the aerodynamic characteristics.
However, such experimental evaluation based on an actual model as described above requires much time and a high cost and besides fails to precisely indicate the causal relation between the shape and arrangement of the dimples and the aerodynamic characteristics. Therefore, it frequently occurs that a golf ball designed newly based on a result of evaluation obtained by an experiment does not exhibit an intended performance. In such an instance as just described, it is necessary to design and produce a prototype of a ball over again and verify the aerodynamic characteristics of the ball every time, and this requires further increase in time and cost. Therefore, the experimental evaluation described above has a problem in that a ball cannot be developed efficiently.
Japanese Patent Laid-open No. 2002-358473 discloses a simulation method which has some relation to the invention of the present application.